Recombinant lactic acid bacteria and the use thereof in oral universal influenza vaccine

ABSTRACT

The present invention relates to an oral universal influenza vaccine comprising recombinant lactic acid bacteria which express proteins including but not limited to ferritin protein plus highly-conserved stem fragment of hemagglutinin (HA) proteins expressed in all known influenza viruses. The present invention also relates to the recombinant protein comprising the highly-conserved stem fragment of HA and ferritin proteins.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority from the U.S. provisional patent application Ser. No. 62/257,242 filed Nov. 19, 2015, and the disclosure of which is incorporated herein by reference in its entirety

TECHNICAL FIELD

The present invention relates to a recombinant lactic acid bacteria and the use thereof in an oral universal influenza vaccine. In particular, the present invention relates to a recombinant lactic acid bacteria expressing highly-conserved stem-fragment of hemagglutinin (HA) proteins which are expressed in all known Influenza viruses, and the use thereof in an oral formulation of a universal influenza vaccine.

BACKGROUND OF THE INVENTION

Global out-breaks of influenza virus continuous to cause a considerable morbidity and mortality. According to the Centers of Disease Control and Prevention (CDC), seasonal influenza leads to over 200,000 hospitalization and 36,000 deaths each year worldwide. In addition, the death rate and the associated economic costs in poultries are enormously as all poultries in the same farm and in close vicinity are terminated if one bird was tested positive. Currently, the best strategy to prevent influenza infection is through vaccination. Given the fact that there are many influenza viruses and their antigenic structures, especially the head domain region, are always changing, the seasonal vaccine components must be frequently updated and modified in order to provide protection against continuous emerging viral strains. The currently available influenza vaccines are not universal which target the head domain of hemagglutinin (HA) on the surface of influenza viruses. It is well known that the globular head domains of hemagglutinin (HA) of influenza virus are highly variable with a high mutation rate. This obviously limits the therapeutic effectiveness of the currently used head-directed influenza vaccines against variant, mutated and drifted variants influenza viruses.

The head domain region is so variable from year to year and that is why new vaccines are needed in order to keep up with the ever changing virus strains every season. Determining the likelihood that a particular influenza vaccine chosen would protect a person from influenza-related illness, the similarity between the influenza viruses and the influenza vaccine designed to protect against is crucial. The development of the traditional influenza vaccine currently used includes the prediction of which viruses should be included in the development of injectable vaccine requires many months in advance in order for vaccine to be produced and delivered on time to deal with constantly mutating influenza viruses (known as drift) every year. Every year, the World Health Organization (WHO) predicts which strains of the influenza virus are most likely to be circulating in the next year allowing pharmaceutical companies to develop vaccines that will provide the best immunity and protection against these strains. The vaccine is reformulated each season for a few specific flu strains but does not include all strains active in the world during the current season and the following seasons and years. It takes about six months for the manufacturers to formulate and produce the millions doses required to deal with the seasonal epidemic. Occasionally, a new or overlooked strain becomes prominent during that season. When the influenza vaccine developed failed to match the circulating viruses, it is possible that no benefit and protection from influenza vaccine injected could occur. It is also possible to get infected just before vaccination and became sick because the administered vaccine in general takes about two weeks to become effective. If the virus changes itself and is able to infect people and spread, an influenza pandemic—a world outbreak of the disease—could begin. No one can predict for sure when an influenza pandemic strikes. A continuous search and modification of “NEW” vaccine for injection by drug companies is needed for the coming influenza pandemic every year. However, prediction and estimation of type(s) of influenza pandemic are obviously not reliable and the process is tedious in view of the expected continuous mutation of the structure of hemagglutinin and type(s) of influenza involved. A wrong prediction can result in a great loss of enormous amount of money and human lives. Most importantly, a wrong prediction of the administered vaccine cannot provide proper protection for humans, poultries and other livestock against influenza infection.

Current influenza vaccination in poultries and human utilizes injectable form (liquid) of dead/inactivated antigen usually via intra-muscular route. Despite the fact that this is the most common route of administration, the procedures require trained personnel (i.e. nurses, doctors, trained farmers) to carry out vaccination procedures. Missed dose occasionally occurs which obviously curtails the overall effectiveness of the influenza vaccination. Also, the traditional vaccination of poultries is labor-intensive and very tedious to work with. On the other hand, the traditional influenza vaccines in liquid form required to be refrigerated at 2-8° C. which is obviously a disadvantage in some areas i.e. hot deserts in Sub-Sahara African and poor rural areas in China where a shortage of electricity as well as poor transportation are common problems. Besides, current vaccines are attenuated pathogenic microorganism which carries the risk that immune reactions triggered against the carrier itself and reduce the efficacy of the booster vaccine. In addition, vaccine in liquid form contains preservatives which some people believe that these preservatives pose health hazards which are related to neurological disorders after vaccine injections. For instance, Autism children are suspected to be related to use of the liquid-form vaccines with the presence of preservatives. Last but not least, the shelf-life of the liquid-form vaccine is rather short i.e. usually less than 3 months which obviously is a disadvantage.

Comparatively, the stem domains of hemagglutinin (HA) are highly conserved across divergent groups of influenza virus strains known (FIG. 6). Therefore, they can trigger the production of broadly neutralizing antibodies and confer the heterologous protections against divergent groups of influenza virus strains.

Ferritin is a globular protein complex consisting of 24 protein subunits and is the primary intracellular iron-storage protein in both prokaryotes and eukaryotes, keeping iron in a soluble and non-toxic form. The protein is produced by almost all living organisms, including algae, bacteria, higher plants, and animals. Ferritin is found in most tissues as a cytosolic protein, but small amounts are secreted into the serum where it functions as an iron carrier. It has been reported that the introduction of ferritin to antigen could enhance the antigenicity of the antigen involved. This would elicit a broader and more potent immunity than the traditional influenza vaccines.

There exists a need for a pharmaceutically acceptable carrier of influenza vaccines that contain these highly-conserved stem domains of HA proteins coupled to ferritin proteins. Lactic acid bacteria (LAB) are one of the most suitable candidates including Lactobacillus sp. because they are Generally Regarded As Safe (GRAS) which can be non-pathogenic carriers for oral vaccine. Techniques of transforming LAB are well developed and a variety of plasmids is available in the market for controlling and modulating the expression of the desired proteins. Preservation and storage of the transformed LAB are also safe and convenient. They are considered as harmless to humans and animals including livestock with a good record of safe uses as food products. Lactic acid bacteria, especially Lactobacillus casei, are food grade microorganisms and are safe for human and animals consumption.

SUMMARY OF THE INVENTION

Accordingly, a first aspect of the present invention relates to a recombinant lactic acid bacteria transformed with an expression vector that contains a DNA sequence encoding the highly-conserved stem domains of influenza hemagglutinin, the ferritin protein, and other regions. Said other regions may include but not limited to an orange fluorescent protein (OFP) which enhances the immunogenicity, a linker between the OFP and the highly-conserved stem domains of influenza hemagglutinin (HA), and a linker between the highly-conserved stem domains of influenza HA and the ferritin protein. In an exemplary embodiment, the encoding sequences of OFP and stem domains of influenza HA are modified to enhance the immunogenicity of the expressed protein against human and other animals and/or expression efficiency in the host cells after transformation. The expressed proteins of OFP, the stem domains of influenza HA, and the ferritin protein from said DNA sequence are therefore linked by said corresponding linker.

The present modified encoding sequences of the OFP and stem domains of influenza HA are preferably for Lactobacillus strains including but not limited to Lactobacillus casei, Lactobacillus acidophilus, and Lactobacillus plantarum. It is also suitable for other LAB such as Lactococcus, e.g., Lactococcus lactis.

The expression vector that can be used in the present invention is preferably an expression vector for gram-positive host, which includes but not limited to pTRKH3 vector, pMSP3535, pDL378 and other kinds of gram-positive expression vectors. In a preferred embodiment, pTRKH3 vector is used.

The influenza that the present recombinant LAB can cause immunogenicity in a human or other animals includes but not limited to H1, H3, and H5 subtypes, since the modified stem domains of influenza HA expressed in the present recombinant LAB are highly conserved in influenza viruses, which could elicit broadly neutralizing antibodies against a wide variety of influenza strains.

The present recombinant LAB can be formulated into different pharmaceutically acceptable forms including but not limited to powder, pills, capsules, liquid, and tablets. In a preferred embodiment, the present recombinant LAB is administered orally to a subject which is human or other animals. However, other administration route which may cause immuno-rejection to the present recombinant LAB should be avoided, e.g., direct injection of the LAB in general subcutaneously or intravenously is known to cause allergic reaction in the recipient.

A second aspect of the present invention relates to a recombinant protein expressed from the DNA sequence encoding the highly-conserved stem domains of influenza hemagglutinin, the ferritin protein, and other regions of the first aspect of the present invention and isolated from the transformed host cells. It should be understood that any conventional method which can be used in transforming an expression vector into a gram-positive host cell such as electroporation can be employed. It should be understood that the highly-conserved stem domains of influenza hemagglutinin expressed from the DNA sequence of the present invention has the ability to induce antibody in the recipient even in the absence of the ferritin protein and other regions of the recombinant protein. In other words, the recombinant protein of the present invention can be the highly-conserved stem domains of the influenza hemagglutinin alone.

A third aspect of the present invention relates to a use of the recombinant lactic acid bacteria according to the first aspect of the present invention or the recombinant protein according to the second aspect of the present invention in the manufacture of a medicament, e.g., a vaccine, for the treatment of influenza by inducing antibody in a subject against a variety of influenza viruses. The medicament according to the third aspect of the present invention is preferably an oral formulation comprising the recombinant lactic acid bacteria or the recombinant protein. The oral formulation comprising the recombinant protein of the present invention further comprises a pharmaceutically acceptable carrier such as a capsule, tablet, salt, buffer, ester, etc. The oral formulation comprising the recombinant lactic acid bacteria of the present invention is in powder form, pills, capsules, tablets, liquid, or buffer, etc. The influenza viruses which the antibody induced by the recombinant lactic acid bacteria or the recombinant protein can target and bind to comprise H1, H3 and H5 subtypes, and other H subtypes of influenza viruses. In a preferred embodiment, the oral formulation comprising an effective amount of the recombinant lactic acid bacteria of the present invention is administered to a subject in needs thereof. Said subject includes human and other animals. When the subject is a small animal such as mouse, the effective amount of the recombinant lactic acid bacteria in said oral formulation is about 1×10⁹ cfu and the oral formulation is administered once daily for three consecutive days on a weekly basis and for two consecutive weeks.

These and other examples and features of the present invention and methods will be set forth in part in the following Detailed Description. This Summary is intended to provide an overview of the present invention, and is not intended to provide an exclusive or exhaustive explanation. The Detailed Description below is included to provide further information about the present disclosures and methods.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic diagram depicting the design of the DNA insert into an expression vector for transformation into a Lactobacillus strain according to a preferred embodiment of the present invention: Region 1 represents a modified DNA sequence of orange fluorescent protein (OFP); Region 2 represents a modified DNA sequence of influenza HA stem fragment; Region 3 represents a DNA sequence of ferritin; two small brackets represent two linkers for linking up the DNA sequences of the OFP and influenza HA stem fragment and those of the influenza HA stem fragment and the ferritin, respectively.

FIG. 2 shows the result of an agarose gel analysis of Lactobacillus casei transformed clones with an expression vector containing the DNA insert depicted in FIG. 1: (M) DNA marker: (L) PCR amplification from transformed Lactobacillus casei clone for clone confirmation.

FIG. 3 shows the result of an agarose gel analysis of restriction enzyme digested cloned plasmid isolated from transformed Lactobacillus casei clones according to an embodiment of the present invention: (M) DNA marker; (1-4) digested cloned plasmid from Lactobacillus casei transformed clones.

FIG. 4 shows the result of Western blot analysis of influenza hemagglutinin stem fragment-containing recombinant protein (OFP-HIHA10-Foldon-Ferritin) extracted from transformed Lactobacillus casei according to an embodiment of the present invention: (C) proteins extracted from wild-type Lactobacillus casei which serves as control: (1) and (2) proteins extracted from transformed Lactobacillus casei.

FIG. 5 shows the result of Western blot analysis of mouse serum two weeks after oral administration of the transformed Lactobacillus casei: (1) PBS only; (2) wild-type Lactobacillus casei (1×10⁹ cfu per mouse); and (3) the transformed Lactobacillus casei (1×10⁹ cfu per mouse) according to an embodiment of the present invention, respectively.

FIG. 6 is a schematic diagram showing a structure of influenza hemagglutinin.

FIG. 7 shows the plasmid construction of the expression vector with the desired DNA insert for transformation into Lactobacillus casei according to a preferred embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

References in the specification to “one embodiment”, “an embodiment”, “an example embodiment”, etc., indicate that the embodiment described can include a particular feature, structure, or characteristic, but every embodiment may not necessarily include the particular feature, structure, or characteristic. Moreover, such phrases are not necessarily referring to the same embodiment. Further, when a particular feature, structure, or characteristic is described in connection with an embodiment, it is submitted that it is within the knowledge of one skilled in the art to affect such feature, structure, or characteristic in connection with other embodiments whether or not explicitly described.

Values expressed in a range format should be interpreted in a flexible manner to include not only the numerical values explicitly recited as the limits of the range, but also to include all the individual numerical values or sub-ranges encompassed within that range as if each numerical value and sub-range is explicitly recited. For example, a concentration range of “about 0.1% to about 5%” should be interpreted to include not only the explicitly recited concentration of about 0.1 wt. % to about 5 wt. %, but also the individual concentrations (e.g., 1%, 2%, 3%, and 4%) and the sub-ranges (e.g., 0.1% to 0.5%, 1.1% to 2.2%, and 3.3% to 4.4%) within the indicated range.

As described herein, the terms “a” or “an” are used to include one or more than one and the term “or” is used to refer to a nonexclusive “or” unless otherwise indicated. In addition, it is to be understood that the phraseology or terminology employed herein, and not otherwise defined, is for the purpose of description only and not of limitation. Furthermore, all publications, patents, and patent documents referred to in this document are incorporated by reference herein in their entirety, as though individually incorporated by reference. In the event of inconsistent usages between this document and those documents so incorporated by reference, the usage in the incorporated reference should be considered supplementary to that of this document; for irreconcilable inconsistencies, the usage in this document controls.

In the methods of manufacturing described herein, the steps can be carried out in any order without departing from the principles of the invention, except when a temporal or operational sequence is explicitly recited. Recitation in a claim to the effect that first a step is performed, and then several other steps are subsequently performed, shall be taken to mean that the first step is performed before any of the other steps, but the other steps can be performed in any suitable sequence, unless a sequence is further recited within the other steps. For example, claim elements that recite “Step A, Step B, Step C, Step D, and Step E” shall be construed to mean step A is carried out first, step E is carried out last, and steps B, C, and D can be carried out in any sequence between steps A and E, and that the sequence still falls within the literal scope of the claimed process. A given step or sub-set of steps can also be repeated.

Furthermore, specified steps can be carried out concurrently unless explicit claim language recites that they be carried out separately. For example, a claimed step of doing X and a claimed step of doing Y can be conducted simultaneously within a single operation, and the resulting process will fall within the literal scope of the claimed process.

Definitions

The singular forms “a,”, “an” and “the” can include plural referents unless the context clearly dictates otherwise.

The term “about” can allow for a degree of variability in a value or range, for example, within 10%, or within 5% of a stated value or of a stated limit of a range.

The term “independently selected from” refers to referenced groups being the same, different, or a mixture thereof, unless the context clearly indicates otherwise. Thus, under this definition, the phrase “X1, X2, and X3 are independently selected from noble gases” would include the scenario where, for example, X1, X2, and X3 are all the same, where X1, X2, and X3 are all different, where X1 and X2 are the same but X3 is different, and other analogous permutations.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

The present invention is not to be limited in scope by any of the following descriptions. The following examples or embodiments are presented for exemplification only.

EXAMPLES

The embodiments of the present invention can be better understood by reference to the following examples which are offered by way of illustration. The present invention is not limited to the examples given herein.

Example 1—Design of DNA Insert and Transformation of Expression Vector Containing the Same in Host Cell

FIG. 1 shows the design of DNA insert comprising a modified orange fluorescent protein (OFP) encoding sequence (Region 1). The sequence is originated from Cerianthus sp. (https://www.ncbi.nlm.nih.gov/protein/31616579?report=genbank&log$=protalign&blast_rank=1&RID=4NXR513S01R)). The protein expressed from this modified OFP encoding sequence can enhance the immunogenicity of the recombinant protein of the present invention in the recipient. The modified encoding sequence of OFP also matches the codon preference of LAB in general. However, other commercially available fluorescent protein having the foregoing characteristics can also be used in the DNA insert.

The DNA insert of FIG. 1 also comprises a modified influenza hemagglutinin stem fragment encoding sequence (Region 2), which is referenced to protein sequences disclosed in Mallajosyula et al. (2014)(http://www.pnas.org/content/111/25/E2514.short). Differing from the disclosed sequences in Mallajosyula et al., reverse translation from one of the disclosed sequences followed by codon optimization to Lactobacillus casei are done, and some modifications are made in the DNA sequence after reverse translation for optimization purposes. A T4 bacteriophage fibritinfoldon is also encoded in the underlined sequence in Region 2 as shown in FIG. 1.

The DNA insert of FIG. 1 further comprises an encoding sequence of ferritin protein (Region 3), which is originated from Helicobacter pylori (https://www.ncbi.nlm.nih.gov/protein/446871934?report=genbank&log$=protalign%blast_rank=1&RID=4KJ8G6K0016).

Between Region 1 and Region 2, the DNA insert of FIG. 1 also comprises a first linker which is a poly-His tag linker. The first linker comprises an Xa protease encoding sequence and a restriction site of KpnI, before the poly-His encoding sequence.

Between Region 2 and Region 3, the DNA insert of FIG. 1 further comprises a second linker. The second linker comprises TEV protease encoding sequence and a restriction site of AgeI.

The sequence of the DNA insert of FIG. 1 is also represented by SEQ ID NO: 1. Optionally, a sequence comprising at least one restriction site can be inserted before and/or after the start codon and stop codon of the DNA insert. For example, NcoI and NdeI restriction sites can be inserted before the start codon; BamHI restriction site can be inserted after stop codon.

The DNA sequence as shown in FIG. 1 (or SEQ ID NO: 1) is cloned in the pTRKH3 expression vector for protein expression in the transformed Lactobacillus casei. FIG. 7 shows the plasmid construction map of said pTRKH3 expression vector inserted with the DNA encoding sequence of SEQ ID NO: 1.

It should be understood that the order of different regions in the DNA insert as described in the present invention can be changed, provided that the expressed proteins from the Lactobacillus casei transformed with said expression vector with these different DNA inserts having different combinations of said regions are capable of inducing antibody against the variety of H subtype influenza viruses in the subject that receives the formulation comprising the transformed Lactobacillus casei. For example, these different inserts may have the following combinations of different regions:

-   -   (i) Region 1 (OFP) is followed by Region 3 (ferritin protein)         and then Region 2 (stem domain of influenza HA), which encoding         sequence is represented by SEQ ID NO: 2;     -   (ii) Region 2 (stem domain of influenza HA) is followed by         Region 1 (OFP) and then Region 3 (ferritin protein), which         encoding sequence is represented by SEQ ID NO: 3;     -   (iii) Region 2 (stem domain of influenza HA) is followed by         Region 3 (ferritin protein) and then Region 1 (OFP), which         encoding sequence is represented by SEQ ID NO: 4;     -   (iv) Region 3 (ferritin protein) is followed by Region 1 (OFP)         and then Region 2 (stem domain of influenza HA), which encoding         sequence is represented by SEQ ID NO: 5;     -   (v) Region 3 (ferritin protein) is followed by Region 2 (stem         domain of influenza HA) and then Region 1 (OFP), which encoding         sequence is represented by SEQ ID No: 6.         It is also possible to only include the encoding sequence of         Region 2 into the expression vector, from which the protein         expressed can still induce antibody against said variety of H         subtype influenza viruses in said subject.

To confirm positive clones. PCR amplification is employed to screen and identify Lactobacillus casei successfully transformed with pTRKH3 expression vector containing the DNA insert of SEQ ID NO: 1, namely OFP-H1HA10-Foldon-Ferritin encoding sequence. In FIG. 2, PCR amplification products from positive clones are analyzed by gel electrophoresis in 1% agarose gel. A pair of forward and reverse primers are used for the amplification, namely SEQ ID NO: 8 and SEQ ID NO: 9. The expected length of the PCR product is 1,766 bp, in which the corresponding band on the gel from the lane loaded with the PCR product is between 1,650 bp and 2,000 bp with respect to the DNA marker next to the lane of the PCR product. The result indicates that the expression vector, pTRKH3, containing the DNA insert of SEQ ID NO: 1 comprising said modified OFP encoding sequence, modified influenza HA stem fragment encoding sequence and ferritin protein encoding sequence has high transformation efficiency. Positive clones so screened are subject to further confirmation and studies.

The DNA encoding sequence of influenza hemagglutinin stem fragment (H1HA10-Foldon) is isolated from the expression vector extracted from the transformed positive clones confirmed in FIG. 2. Under double-digestion by using two specific restriction enzymes (KpnI and AgeI), the digested expression vector samples extracted from the positive clones are analyzed by agarose gel (1%) electrophoresis. FIG. 3 shows that there are two distinct bands in four samples, and it is confirmed that the expression vector used in this example is successfully transformed inside the host bacteria.

Example 2—Expression of Recombinant Protein Comprising Influenza HA Stem Fragment

The positive transformed Lactobacillus casei clones from Example 1 which are successfully selected are capable of expressing the influenza hemagglutinin stem-fragment. To further confirm that the corresponding target fragment is expressed in the transformed Lactobacillus casei, Western blot is performed to assess the expression efficiency of the hemagglutinin stem fragment inside the transformed Lactobacillus casei. Positive clones are cultured in MRS broth supplemented with 100 μg/ml erythromycine at 37° C. with shaking at 250 rpm in anaerobic conditions for 72 hours.

After that, the bacterial cell suspension is collected and the collected cells are lysed to collect the cytosolic proteins. In FIG. 4, two samples are run in SDS gel followed by Western blot analysis. The significant band indicates the presence of the expression of the influenza hemagglutinin stem fragment from the transformed Lactobacillus casei. The amino acid sequence of the recombinant protein containing the modified OFP, modified influenza HA stem fragment (H1HA10-Foldon) and ferritin protein (OFP-H1HA10-Foldon-Ferritin) is represented by SEQ ID NO: 7.

Example 3—In Vivo Study of Immunogenicity of Recombinant Lactic Acid Bacteria

BALB/c mice (6-8 weeks) (n=7) are randomly divided into three groups. Three groups are orally administered with three different formulations: PBS (Group 1), wild-type Lactobacillus casei resuspended in 200 μl PBS (1×10⁹ cfu per mouse) (Group 2); and transformed Lactobacillus casei confirmed in Examples 1 and 2 resuspended in 200 μl PBS (1×10⁹ cfu per mouse) (Group 3), respectively. Oral gavage is repeated three times (once daily, consecutive three days) on a weekly basis for two consecutive weeks. Mice are boosted twice after one week. Blood samples are collected from tail vein at week 3, 5, 7, 9 and 15 after oral gavage of three different formulations, and stored at −80° C. before testing for the presence of the antibodies interested. Also, the weight of each mouse is recorded weekly during the course of feeding period so as to monitor the health conditions of individual mouse after consumption of Lactobacillus casei. No loss of weight is observed and all mice are alive after the course of oral gavage as described hereinbefore.

The confirmed positive clones of expression vector containing the encoding sequence of OFP-H1HA10-Foldon-Ferritin is transformed into DH50α for generation of antibodies. The antibodies so generated are purified using His-bind fractogel column. The purified antibodies are loaded in SDS-PAGE, probed with mouse antibody from mouse serum and detected with HRP-conjugated goat anti-mouse IgG antibody (1:1000) and visualized with ECL Western blotting substrate. After feeding mice with transformed Lactobacillus casei, mouse serum is collected after two weeks of oral feeding and the antibody against the influenza hemagglutinin stem fragment is detected in mouse serum whereas no corresponding antibody is detected in mice orally fed with PBS or wild-type Lactobacillus casei. These results suggest that mice orally fed with transformed Lactobacillus casei generate the corresponding antibody against hemagglutinin stem fragment.

INDUSTRIAL APPLICABILITY

The present recombinant lactic acid bacteria is useful in manufacturing into a vaccine which is safe to be orally administered into a subject such as human and other animals (e.g., livestock). The expressed recombinant protein isolated and purified from a host transformed with the expression vector containing the encoding sequence of the modified influenza hemagglutinin may be used in manufacturing of the vaccine. The vaccine is not limited to oral formulation but it can also include other forms such as injectable form, provided that it does not induce immune-rejection.

Deposition of Microorganism

Pursuant to the requirements under PCT Rule 13bis, the present modified recombinant Lactobacillus casei has been deposited at the following International Depositary Authority:

Name of Deposit Institute: Guangdong Microbial Culture Collection Center (GDMCC), Guangdong Institute of Microbiology Address of Deposit Institute: No. 59 Building, 100 Xianlie Central Road, Guangzhou 510070, China Date of Deposit: 18 Nov. 2016 GDMCC No.: 60113 

1. A recombinant lactic acid bacterial cell transformed with an expression vector containing an encoding sequence for encoding a modified fluorescent protein, a modified stem domain of influenza hemagglutinin, a ferritin protein, and two linkers.
 2. The recombinant lactic acid bacterial cell of claim 1, wherein said modified fluorescent protein is orange fluorescent protein originated from Cerianthus sp.
 3. The recombinant lactic acid bacterial cell of claim 1, wherein said modified stem domain of influenza hemagglutinin comprises a H1HA10 stem fragment and T4 bacteriophage fibritinfoldon.
 4. The recombinant lactic acid bacterial cell of claim 1, wherein said ferritin protein is originated from Helicobacter pylori.
 5. The recombinant lactic acid bacterial cell of claim 1, wherein said encoding sequence is one of the SEQ ID NOs: 1-6.
 6. The recombinant lactic acid bacterial cell of claim 5, wherein said encoding sequence is SEQ ID NO:
 1. 7. The recombinant lactic acid bacterial cell of claim 1, wherein said lactic acid bacterial cell is from the strains comprising Lactobacillus sp. and Lactococcus sp.
 8. The recombinant lactic acid bacterial cell of claim 1, wherein said expression vector is an expression vector that is for expressing protein in gram-positive bacterial host cells.
 9. The recombinant lactic acid bacterial cell of claim 1, wherein said lactic acid bacterial cell is from Lactobacillus casei.
 10. The recombinant lactic acid bacterial cell of claim 1, wherein said expression vector is pTRKH3.
 11. The recombinant lactic acid bacterial cell of claim 6, wherein said two linkers comprises a first linker positioned between the encoding sequence of the modified fluorescent protein and modified stem domain of influenza hemagglutinin, and a second linker positioned between the encoding sequence of the modified stem domain of influenza hemagglutinin and ferritin protein.
 12. The recombinant lactic acid bacterial cell of claim 11, wherein said first linker comprises an Xa protease encoding sequence, a restriction site of KpnI, and a poly-His encoding sequence.
 13. The recombinant lactic acid bacterial cell of claim 11, wherein said second linker comprises TEV protease encoding sequence and a restriction site of AgeI.
 14. The recombinant lactic acid bacterial cell of claim 11, wherein said modified fluorescent protein and modified stem domain of influenza hemagglutinin are coupled together by the first linker while the modified stem domain of influenza hemagglutinin and ferritin protein are coupled together by the second linker.
 15. The recombinant lactic acid bacterial cell of claim 6, wherein said expression vector expresses a recombinant protein with an amino acid sequence of SEQ ID NO:
 7. 16. A recombinant protein or a protein fragment of a stem domain of influenza hemagglutinin comprising an amino acid sequence of SEQ ID NO: 7 or being encoded from an encoding sequence of any one of SEQ ID NOs: 2-6 for inducing antibody in a host against a variety of influenza viruses.
 17. The recombinant protein or protein fragment of a stem domain of influenza hemagglutinin of claim 16, wherein said influenza viruses comprise H1, H3, H5, and other H subtypes.
 18. The recombinant protein or protein fragment of a stem domain of influenza hemagglutinin of claim 16, wherein said host comprises bacterial, human and animal cells.
 19. A method for treating influenza caused by a variety of influenza viruses comprising orally administering a composition comprising the recombinant lactic acid bacterial cell of claim 1 to a subject in need thereof.
 20. (canceled)
 21. The method of claim 19, wherein said medicament is orally administered to said subject once daily for three consecutive days on weekly basis and for two consecutive weeks.
 22. (canceled)
 23. The method of claim 19, wherein said variety of influenza viruses comprises H1, H3, H5 and other H subtypes.
 24. The method of claim 19, wherein said composition is formulated into a form comprising powder, pills, capsules, liquid, and tablets.
 25. A method for treating influenza caused by a variety of influenza viruses comprising orally administering a composition comprising the recombinant protein or protein fragment of a stem domain of influenza hemagglutinin of claim 16 and a pharmaceutically acceptable carrier to a subject in need thereof.
 26. (canceled)
 27. The method of claim 25, wherein said variety of influenza viruses comprises H1, H3, H5, and other H subtypes. 28-32. (canceled) 